New! View global litigation for patent families

US6456648B1 - Code tracking loop with automatic power normalization - Google Patents

Code tracking loop with automatic power normalization Download PDF

Info

Publication number
US6456648B1
US6456648B1 US10034867 US3486701A US6456648B1 US 6456648 B1 US6456648 B1 US 6456648B1 US 10034867 US10034867 US 10034867 US 3486701 A US3486701 A US 3486701A US 6456648 B1 US6456648 B1 US 6456648B1
Authority
US
Grant status
Grant
Patent type
Prior art keywords
signal
loop
code
error
power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
US10034867
Inventor
Aykut Bultan
Donald Grieco
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
InterDigital Technology Corp
Original Assignee
InterDigital Technology Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Grant date

Links

Images

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/707Spread spectrum techniques using direct sequence modulation
    • H04B1/7073Synchronisation aspects
    • H04B1/7085Synchronisation aspects using a code tracking loop, e.g. a delay-locked loop
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69Spread spectrum techniques
    • H04B1/707Spread spectrum techniques using direct sequence modulation
    • H04B1/709Correlator structure
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00Arrangements for synchronising receiver with transmitter
    • H04L7/0016Arrangements for synchronising receiver with transmitter correction of synchronization errors
    • H04L7/002Arrangements for synchronising receiver with transmitter correction of synchronization errors correction by interpolation
    • H04L7/0029Arrangements for synchronising receiver with transmitter correction of synchronization errors correction by interpolation interpolation of received data signal

Abstract

The present invention is a receiver, included in a user equipment (UE), of a code division multiple access (CDMA) communication system which includes the UE and a plurality of base stations. The UE is in communication with one of the plurality of base stations and receives a communication signal from the base station through the receiver. The communication signal is correlated by said receiver using a delay locked code tracking loop, that estimates and tracks a channel delay of the communication signal. The tracking loop comprises a reference code generator for generating a reference code signal and an interpolator for generating timed signal versions in response to the receipt of said communication. A timed signal correlator, also included in the tracking loop for correlating at least two of the timed signal versions with the code reference signal. The result of the correlation is used for generating an error signal. An automatic power normalization loop (APN), that is responsive to the interpolator, generates a power error signal that normalizes the error signal through a normalization circuit.

Description

The application claims priority from Provisional Patent Application No. 60/326,308, filed Oct. 1, 2001.

BACKGROUND

The present invention relates to a code tracking system for a receiver of a code division multiple access (CDMA) communication system. More specifically, the present invention relates to a second order code tracking system for more effectively removing the timing difference between the transmitted code and the received code.

Synchronization is an important task in any kind of telecommunication. There are several levels of synchronization, such as, carrier, frequency, code, symbol, frame and network synchronization. In all these levels, synchronization can be distinguished into two phases, which are acquisition (initial synchronization) and tracking (fine synchronization).

A typical wireless communication system sends downlink communications from a base station to one or a plurality of User Equipments (UEs) and uplink communications from UEs to the base station. A receiver within the UE works by correlating, or despreading, the received downlink signal with a known code sequence. The sequence must be exactly synchronized to the received sequence in order to get the maximal output from the correlator.

The receiver should be able to easily adapt to a change in the environment of a radio line changing without ceasing operation. In order to accomplish this, present receivers gather as much of the transmitted signal energy as possible in order to maximize the signal-to-noise ratio. In multi-path fading channels, however, the signal energy is dispersed over a certain amount of time due to distinct echo paths and scattering. One crucial task of the receiver is thus to estimate the channel to improve its performance. If the receiver has information about the channel profile, one way of gathering signal energy is then to assign several correlator branches to different echo paths and combine their outputs constructively, a structure known as the RAKE receiver.

The RAKE receiver has several fingers, one for each echo path, and in each finger, the path delay with respect to some reference delay such as a direct or the earliest received path, must be estimated and tracked throughout the transmission. The estimation of the paths initial position in time is obtained by using a multi-path search algorithm. The multi-path search algorithm does an extensive search through correlators to locate the paths with a chip accuracy. After these initial positions are found, the tracking units generate accurate estimates for the delays of several multi-path components by means of early-late timing error detectors and utilize these estimates for the different delays to shift the phase of the codes. This type of tracking unit is known as an early-late gate synchronizer. A delay-locked loop (DLL) is commonly used to implement the early-late gate synchronizer. Illustrated in FIG. 1 is a block diagram of this delay-locked loop. The bandwidth of the Code Tracking Loop (CTL) determines the noise filtering capability of the synchronizer. The narrower the bandwidth, the more robust the synchronizer is to distortion from noise and less sensitive to small signal changes. The bandwidth of the loop depends on the parameters of the loop filter (alpha, beta), total loop gain (KT), and input signal power level (Pin). Damping ratio of the loop also depends on the same parameters. Damping ratio of the loop determines the stability of the loop. Although the parameters of the loop can be fixed, it is very difficult to fix the input signal level.

Most of the digital receivers employ some form of Automatic Gain Control (AGC) in their physical layers. Although AGC limits the input signal level, the dynamic level of the signal level is still large. This is due to the fact that AGC is actually designed to prevent the Analog to Digital Converter (ADC) from entering saturation.

Since the dynamic range of the input signal level is not effectively limited, the bandwidth and damping ratio of the code tracking loop changes with input signal power. This results in degradation in performance for the code tracking loop.

Accordingly, there exists a need for a code tracking loop that maintains the bandwidth and damping ratio of the loop regardless of changes with the input signal power level.

Other objects and advantages of the present invention will become apparent after reading the description of the preferred embodiment.

SUMMARY

The present invention is a receiver, included in a user equipment (UE), of a code division multiple access (CDMA) communication system which includes the UE and a plurality of base stations. The UE is in communication with one of the plurality of base stations and receives a communication signal from the base station through the receiver. The communication signal is correlated by said receiver using a delay locked code tracking loop, that estimates and tracks a channel delay of the communication signal. The tracking loop comprises a reference code generator for generating a reference code signal and an interpolator for generating timed signal versions in response to the receipt of said communication. A timed signal correlator, also included in the track loop for correlating at least two of the timed signal versions with the code reference signal. The result of the correlation is used for generating an error signal. An automatic power normalization loop (APN), which is responsive to the interpolator, generates a power error signal that is used to normalize the error signal through a normalization circuit.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is a block diagram of a prior art delay-locked tracking loop.

FIG. 2 is a block diagram of a delay-locked code tracking loop with automatic power normalization in accordance with the present invention.

FIG. 3 Is a flow diagram of the delay-locked code tracking loop of the present invention.

FIG. 4 is a block diagram of an exemplary loop filter included in the delay-locked tracking loop of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The preferred embodiment will be described with reference to the drawing figures wherein like numerals repeat like elements throughout.

Illustrated in FIG. 2 is a block diagram of the delay-locked code tracking loop (DCTL) 10 in accordance with the preferred embodiment of the present invention. The DCTL comprises an interpolator 11, two integrate and dump devices 12 a, 12 b, two squaring devices 13 a, 13 b, a normalization device 14, a loop filter 15, a code generator 16, an accumulator 17, a limiter 18, a quantizer 19, a gain circuit 9, and an automatic power normalization loop (APN) 20. The delay-lock code tracking loop 10 receives an input signal x (t-T), where T is the timing error in the received signal. Since the timing error is confined to −Tc to Tc, where Tc is the chip duration using the multi-path search algorithm, the only way to shift the incoming signal is by using mathematical interpolation. Accordingly, the interpolator 11, coupled to the integrate devices 12 a, 12 b, the code generator 16, and the APN 20, receives the input signal x (t-T) and creates three outputs: Punctual, Early and Late. As those skilled in the art know, the Early and Late outputs are a half chip early and a half chip late-versions of the punctual output, respectively. They are all obtained by interpolation of the incoming signal x (t-T). After the interpolator 11, down-sampling takes place, all three outputs are preferably down-sampled by an over-sampling ratio of the transmitted signal. The punctual output is the main output of the DCTL 10, the early and late outputs are used only inside the code tracking loop 10 algorithm.

The early and late signals are correlated with the output of the reference code generator 16, such as a pilot code generator, in lower and upper branches of the DCTL using the integrate devices 12 a, 12 b, respectively. Once the outputs of the code generator 16 and the early and late outputs have been correlated, the correlated signals are forwarded to squaring devices 13 a, 13 b, respectively. Since phase synchronization is not acquired at this stage, squaring is used to obtain non-coherent CTL.

After correlation and squaring, the difference of the two branches (early and late) are taken to produce an error signal e(t), which is proportional to the timing error. The error signal e(t) is then power normalized against a power error signal (Pe) by the normalization circuit 14 (to be disclosed hereinafter) and output to the loop filter 15.

The loop filter 15, coupled to the normalization device 14 and the accumulator 17, filters the normalized error signal e(t) and forwards it to the accumulator 17. An exemplary loop filter is a classical proportional integrator (PI) filter, but any first order low-pass filter would be appropriate for the present invention. The PI filter, including a loop filter accumulator 41, has two branches, as shown in FIG. 4. One branch creates a control signal proportional to the current value of the error signal and the other branch produces a signal proportional to the average value of the error signal. These signals are combined after being multiplied by two different constants, alpha and beta. The accumulator 41 inside the PI filter works exactly the same way as the accumulator 17 described below.

The accumulator 17, coupled to the loop filter and a gain circuit 9, receives the filtered error signal from the loop filter 15 and processes the signal. Those having skills in the art know that the accumulator 17 simply adds its current input to its previous output. Initially, the output of the accumulator 17 is set to zero. There is an overflow detection inside the accumulator to limit the output value. The accumulation by the accumulator 17 together with the loop filter 15 is used to obtain the second order feedback loop response. The accumulator 17 then forwards the error signal e(t) to the gain circuit 9.

The gain circuit 9, coupled to the accumulator 17 and a limiter circuit 18, receives the output of the accumulator 17 and adjust the level of the filtered signal to match the interpolator 11 timing shift value. This circuit changes the sign in the timing air signal to correct the timing delay/advance of the incoming signal reference to the code generator 16. Once this is accomplished, the gain circuit 9 forwards the adjusted error signal e(t) to a limiter circuit 18 that limits the over shoot of the error signal if it is above the chip duration—Tc to Tc. The limiter 18 forwards the error signal to the quantizer 19 where the discrete value of the delay estimate is obtained and forwarded back to the interpolator 11. In this design, a thirty-two (32) level quantizer is used to obtain an accuracy of Tc/16. Although any level of quantizer can be used for different levels of delay estimate accuracy.

DCTL is a second order feedback loop. In control system notation, the system function, H(s), for a second order feedback loop can be written as H ( s ) = 2 ζω n s + ω n 2 s 2 + 2 ζω n s + ω n 2 , Equation ( 1 )

Figure US06456648-20020924-M00001

where ξ is the damping ratio and ωn is the natural frequency of the system. These can be written in terms of the parameters of the DCTL as follows:

ω n = 2 P in K T β , Equation ( 2 ) ζ = K T α P in ω n , Equation ( 3 )

Figure US06456648-20020924-M00002

where alpha and beta are the loop filter parameters, KT=KSK is the total open loop gain including the S-curve gain and the external gain, and Pin is the input signal power. The two-sided noise bandwidth of the system is given by W L = ω n ( ζ + 1 4 ζ ) . Equation ( 4 )

Figure US06456648-20020924-M00003

As an example, a Universal Mobile Telecommunications System (UMTS) Frequency Division Duplex (FDD) ULE receiver design with a chip rate of 3.84 MHz and 2 times over-sampling use the following values: spreading factor of 256 for the pilot code, loop gain K=0.01, alpha=0.0141, and beta=0.00001. The values of natural frequency and damping ratio determine the main characteristics of the loop such as stability, gain and phase margins, bandwidth, convergence time, and steady state jitter. These characteristics are fixed during the design and should not change with respect to the input. Otherwise, the DCTL may malfunction and produce unexpected results. However, as seen from equations 2, 3, and 4, they all depend on input signal power, Pin, which may change considerably during the communication process.

In order to overcome the effects of the input signal x (t-T) power level changing, an Automatic Power Normalization loop 20 (APN) is included in the delay-locked tracking loop 10 of the present invention. The APN 20, coupled to the interpolator 11, the code generator 16 and the normalization circuit 11, comprises an integrate and dump circuit 21, a squaring device 22, an adder 24, and a moving average (MA) filter 23. The punctual output from the interpolator 11 is the input to the APN loop 20. The punctual signal is received by the integrate and dump circuit 21 along with the signal from the code generator 16. The integrate and dump circuit 21 is coupled to the code generator 16, the interpolator 11, and the squaring device 22. Similar to the integrate and dump circuits 12 a, 12 b disclosed above, the integrate and dump circuit 21 correlates the punctual signal received from the interpolator 11 with the signal received from the reference code generator 16. Once the two signals are correlated the integrate circuit 21 forwards the correlated signal to the squaring device 22.

The squaring device 22, coupled to the integrate circuit 21 and the adder 24, squares the correlated signal and forwards the squared signal to the adder 24. The adder 24 subtracts the squared output from the squaring device 22 from a reference signal power (P) the reference signal power (P) is a predetermined value and is used in the design of the DLL 10 to set the parameters. As those skilled in the art know, the reference power level (P) may be any predetermined value. The subtracting of the squared signal by the adder 24 results in a power difference signal, which is forwarded to the moving average filter 23.

The Moving Average (MA) filter 23, coupled to the adder 24 and the normalization circuit 14, receives the difference signal and filters it. The MA filter 23 consists of a real valued register of size N, an adder, and a constant multiplier with a factor of 1/N. Each time a new input is passed to the MA filter 23 the register elements are shifted one to the right. The element that came the earliest (on the right most side) is cleared and the current input value is placed in the left most place in the register. After this shift, each element in the register is added. The total value is multiplied by 1/N to produce the average value for the power error signal (Pe). It is preferable that N be selected to be twenty (20), which corresponds to 20 symbols processed. The MA filter size is selected such that it will be insensitive to instantaneous power changes due to fading, however it will compensate for the average input signal level changes. Once the MA filter 23 filters the power difference signal, a filtered power error signal Pe is forwarded to the normalization circuit 14. The normalization circuit 14, coupled to the squaring devices 13 a, 13 b and the APN 20, receives the error e(t) corresponding to the difference between the late and early outputs of the interpolator 11 and the power error signal Pe from the APN 20. In order to normalize the error signal e(t) against the power error signal Pe, the normalization circuit 14 multiplies the error signal e(t) by (P/(P+Pe)), where P is the referenced signal power level used in the APN loop 20.

The normalization of the error signal instead of the input signal results in a reduced number of multiplications (normalization) by a factor equal to the spreading factor. Preferably, integrated into the normalization circuit there is a limiter (not shown) that limits the multiplication factor from 0.1 to 10 or −20 dB to 20 dB. This limiter is used to prevent noise amplification.

The flow diagram of the delay-lock code tracking loop in accordance with the preferred embodiment of the present invention is illustrated in FIG. 3. An input signal in received by the DLL circuit 10 (step 301). The interpolator 11 of the DLL circuit 10 produces the late, early and punctual outputs (step 302). The late and early outputs are correlated with the code generator 16 (step 303 a), and the difference between the correlated signals is determined, producing an error signal e(t) (step 304 a). Simultaneous to the late and early outputs, the punctual output is correlated with the code generator (step 303 b) and subtracted from a predetermined reference power level to produce a power level difference signal (step 304 b). The power level difference signal is then filtered to produce a power level error signal Pe (step 305 b). The error signal corresponding to the late and early outputs, is normalized against the power level error signal Pe from the APN loop 20 (step 306). The normalized error signal is then processed to produce a delay estimate (step 307) which is forwarded back to the input of the DLL tracking loop 10 (step 308).

While the present invention has been described in terms of the preferred embodiment, other variations which are within the scope of the invention as outlined in the claims below will be apparent to those skilled in the art.

Claims (15)

What is claimed is:
1. A code division multiple access (CDMA) communication system including a plurality of communication stations, at least one station comprising a receiver for receiving a communication signal from another station, wherein said communication signal is correlated by said receiver using a delay locked code tracking loop for estimating and tracking a channel delay of said communication, the tracking loop comprising:
a reference code generator for generating a reference code signal;
an interpolator for generating a base version of the received communication signal and a plurality of time offset versions thereof;
a timed signal correlator for correlating each said time offset signal version with said code reference signal and combining the correlations for generating an error signal;
an automatic power normalization loop (APN), for generating a power error signal based on the base signal version and the reference code signal; and
a normalization circuit for normalizing said error signal using said power error signal to generate a normalized error signal used for controlling the generation of the base signal version by the interpolator.
2. The system of claim 1 wherein said APN includes
an APN correlator for correlating the base signal version and the reference code signal to generate a correlated signal;
an adder for subtracting said correlated signal from a power reference signal, producing a power difference signal; and
a filter, responsive to said adder, for filtering said power difference to generate the power error signal.
3. The system of claim 2 wherein said tracking loop further comprises:
a loop filter, coupled to said normalization circuit, for filtering said normalized error signal;
an accumulator, responsive to said loop filter, for accumulating said error signal;
a gain circuit, coupled to the accumulator, for changing the sign in the error signal to correct a timing delay/advance of the received communication signal to the reference code signal; and
a quantizer for generating a discrete value of the delay/advance for controlling the generation of the base signal version by the interpolator.
4. The system of claim 2 wherein said time offset versions are an early version and a late version of said base version.
5. The system of claim 4 wherein said early version is a half chip early and said late version is a half chip late of said base version.
6. A delay locked code tracking loop for estimating and tracking a channel delay of a communication in a code division multiple access (CDMA) communication system including a plurality of communication stations, at least one station comprising a receiver including said tracking loop for receiving the communication from another station, wherein said communication signal is correlated by said receiver using said tracking loop, the tracking loop comprising:
a reference code generator for generating a reference code signal;
an interpolator for generating a base version of the received communication signal and a plurality of time offset versions thereof;
a timed signal correlator for correlating each said time offset signal version with said code reference signal and combining the correlations for generating an error signal;
an automatic power normalization loop (APN), for generating a power error signal based on the base signal version and the reference code signal; and
a normalization circuit for normalizing said error signal using said power error signal to generate a normalized error signal used for controlling the generation of the base signal version by the interpolator.
7. The tracking loop of claim 6 wherein said APN includes
an APN correlator for correlating the base signal version and the reference code signal to generate a correlated signal;
an adder for subtracting said correlated signal from a power reference signal, producing a power difference signal; and
a filter, responsive to said adders, for filtering said power difference to generate the power error signal.
8. The tracking loop of claim 7 further comprising:
a loop filter, coupled to said normalization circuit, for filtering said normalized error signal;
an accumulator, responsive to said loop filter, for accumulating said error signal;
a gain circuit, coupled to the accumulator, for changing the sign in the error signal to correct a timing delay/advance of the received communication signal to the reference code signal; and
a quantizer for generating a discrete value of the delay/advance for controlling the generation of the base signal version by the interpolator.
9. The tracking loop of claim 7 wherein said time offset versions are an early version and a late version of said base version.
10. The tracking loop of claim 9 wherein said early version is a half chip early and said late version is a half chip late of said base version.
11. A method for estimating and tracking a channel delay of a communication in a code division multiple access (CDMA) communication system including a plurality of communication stations, at least one station comprising a receiver for receiving the communication signal from another station, wherein said communication signal is correlated by said receiver using a delay locked tracking loop, the method comprising the steps of:
generating a reference code signal;
interpolating the received communication signal to generate a base version of the communication signal and a plurality of time offset versions thereof;
correlating each said time offset signal version with said code reference signal and combining the correlations to generate an error signal;
generating a power error signal based on the base signal version and the reference code signal; and
normalizing said error signal using said power error signal to generate a normalized error signal used for controlling the generation of the base signal version.
12. The method of claim 11 wherein said step of generating a power error signal includes the steps of:
correlating the base signal version and the reference code signal to generate a correlated signal;
subtracting said correlated signal from a power reference signal, producing a power difference signal; and
filtering said power difference to generate the power error signal.
13. The method of claim 12 further comprising the steps of:
filtering said normalized error signal;
accumulating said error signal;
changing the sign in the error signal to correct a timing delay/advance of the received communication to the reference code signal; and
generating a discrete value of the delay/advance for controlling the generation of the base signal version.
14. The method of claim 11 wherein said time offset versions are an early version and a late version of said base version.
15. The method of claim 14 wherein said early version is a halfchip early and said late version is a half chip late of said base version.
US10034867 2001-10-01 2001-12-27 Code tracking loop with automatic power normalization Active US6456648B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US32630801 true 2001-10-01 2001-10-01
US10034867 US6456648B1 (en) 2001-10-01 2001-12-27 Code tracking loop with automatic power normalization

Applications Claiming Priority (18)

Application Number Priority Date Filing Date Title
US10034867 US6456648B1 (en) 2001-10-01 2001-12-27 Code tracking loop with automatic power normalization
EP20020731342 EP1433266B1 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
DE2002607747 DE60207747D1 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
CA 2462504 CA2462504A1 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
PCT/US2002/011504 WO2003030389A1 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
DE2002631260 DE60231260D1 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
JP2003533462A JP4035108B2 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
EP20090002214 EP2056485A1 (en) 2001-10-01 2002-04-15 User equipment with code tracking loop with automatic power normalization
EP20050025778 EP1638216B1 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
DE2002607747 DE60207747T2 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization
CN 02819382 CN1561582B (en) 2001-10-01 2002-04-15 Tracking loop and method for tracking communication channel delay in code division multiple access (CDMA) system
ES02731342T ES2250650T3 (en) 2001-10-01 2002-04-15 Code tracking loop with automatic power normalization.
DK02731342T DK1433266T3 (en) 2001-10-01 2002-04-15 Kodesporingsslöjfe with automatic power normalization
US10252640 US6633603B2 (en) 2001-10-01 2002-09-23 Code tracking loop with automatic power normalization
US10686057 US7010020B2 (en) 2001-10-01 2003-10-14 Code tracking loop with automatic power normalization
US11338226 US7529292B2 (en) 2001-10-01 2006-01-24 Code tracking loop with automatic power normalization
JP2007032693A JP4227178B2 (en) 2001-10-01 2007-02-13 Code tracking loop with automatic power normalization
US12435105 US20090213911A1 (en) 2001-10-01 2009-05-04 Code tracking loop with automatic power normalization

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US10252640 Continuation US6633603B2 (en) 2001-10-01 2002-09-23 Code tracking loop with automatic power normalization

Publications (1)

Publication Number Publication Date
US6456648B1 true US6456648B1 (en) 2002-09-24

Family

ID=26711478

Family Applications (5)

Application Number Title Priority Date Filing Date
US10034867 Active US6456648B1 (en) 2001-10-01 2001-12-27 Code tracking loop with automatic power normalization
US10252640 Expired - Fee Related US6633603B2 (en) 2001-10-01 2002-09-23 Code tracking loop with automatic power normalization
US10686057 Expired - Fee Related US7010020B2 (en) 2001-10-01 2003-10-14 Code tracking loop with automatic power normalization
US11338226 Expired - Fee Related US7529292B2 (en) 2001-10-01 2006-01-24 Code tracking loop with automatic power normalization
US12435105 Abandoned US20090213911A1 (en) 2001-10-01 2009-05-04 Code tracking loop with automatic power normalization

Family Applications After (4)

Application Number Title Priority Date Filing Date
US10252640 Expired - Fee Related US6633603B2 (en) 2001-10-01 2002-09-23 Code tracking loop with automatic power normalization
US10686057 Expired - Fee Related US7010020B2 (en) 2001-10-01 2003-10-14 Code tracking loop with automatic power normalization
US11338226 Expired - Fee Related US7529292B2 (en) 2001-10-01 2006-01-24 Code tracking loop with automatic power normalization
US12435105 Abandoned US20090213911A1 (en) 2001-10-01 2009-05-04 Code tracking loop with automatic power normalization

Country Status (9)

Country Link
US (5) US6456648B1 (en)
EP (2) EP2056485A1 (en)
JP (2) JP4035108B2 (en)
CN (1) CN1561582B (en)
CA (1) CA2462504A1 (en)
DE (3) DE60207747D1 (en)
DK (1) DK1433266T3 (en)
ES (1) ES2250650T3 (en)
WO (1) WO2003030389A1 (en)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010038665A1 (en) * 2000-03-03 2001-11-08 Jens Baltersee Method and rake receiver for phasor estimation in communication systems
US20020134908A1 (en) * 2001-01-24 2002-09-26 Applied Optoelectronics, Inc. Method for determining photodiode performance parameters
US20020169067A1 (en) * 2001-01-04 2002-11-14 Janssen Marcel J.G. Rejuvenating SAPO molecular sieve by freeze drying
US20030108136A1 (en) * 2001-11-30 2003-06-12 Fan Wang Time recovery circuit and method for synchronizing timing of a signal in a receiver to timing of the signal in a transmitter
US6633603B2 (en) * 2001-10-01 2003-10-14 Interdigital Technology Corporation Code tracking loop with automatic power normalization
US20030202495A1 (en) * 2002-04-30 2003-10-30 Frank Poegel Power normalization in WLAN receivers
US6658242B1 (en) * 1997-12-12 2003-12-02 Thomson Licensing S.A. TDMA wireless telephone system with independently tracked demodulation parameters
US20030231703A1 (en) * 2002-06-17 2003-12-18 Agilent Technologies, Inc. Rake receiver delay line design
US20040088609A1 (en) * 2002-11-04 2004-05-06 Advanced Micro Devices, Inc. Early-late correlation for timing error correction in data communication receivers
US20040170911A1 (en) * 2003-02-26 2004-09-02 Tomoyuki Shimada Electrophotographic photoreceptor, and image forming method, image forming apparatus and process cartridge for image forming apparatus using the electrophotographic photoreceptor
US20040184533A1 (en) * 1997-03-14 2004-09-23 Microsoft Corporation Motion video signal encoder and encoding method
US7006557B2 (en) * 2002-01-31 2006-02-28 Qualcomm Incorporated Time tracking loop for diversity pilots
US20060098719A1 (en) * 2000-01-14 2006-05-11 Jens Baltersee Adaptive code-tracking receiver for direct-sequence code-division multiple access (CDMA) communications over multipath fading channels and method for signal processing in a rake receiver
US7203220B2 (en) 2000-01-14 2007-04-10 Agere Systems Inc. Method and rake receiver for code-tracking in communication systems
US20070121708A1 (en) * 2005-11-28 2007-05-31 Honeywell International, Inc. Discriminator function for GPS code alignment
US20090129458A1 (en) * 2004-11-08 2009-05-21 Interdigital Technology Corporation Method and apparatus for estimating the step-size of an adaptive equalizer
EP2161845A1 (en) * 2007-06-06 2010-03-10 Masshall Limited A multipath tracking device and method in a cdma communication system
US20100215084A1 (en) * 2002-04-29 2010-08-26 Interdigital Technology Corporation Simple and robust digital code tracking loop for wireless communication systems
US20170155422A1 (en) * 2014-11-27 2017-06-01 Lg Electronics Inc. Rake receiver and receiving method thereof
US9923596B2 (en) * 2014-05-15 2018-03-20 Mitsubishi Electric Corporation Demodulation apparatus

Families Citing this family (52)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100373338B1 (en) * 2000-06-24 2003-02-25 주식회사 팬택앤큐리텔 Apparatus for tracking CDMA code timing
GB0028392D0 (en) * 2000-11-22 2001-01-03 Koninkl Philips Electronics Nv A rake receiver
US7010073B2 (en) * 2001-01-19 2006-03-07 Qualcomm, Incorporated Delay lock loops for wireless communication systems
CN100452669C (en) * 2002-11-15 2009-01-14 意大利电信股份公司 Early-late synchronizer having reduced timing jitter
KR100547786B1 (en) * 2003-08-09 2006-01-31 삼성전자주식회사 Moving the timing error detecting method and apparatus in a communication system
US7006840B2 (en) * 2003-09-30 2006-02-28 Interdigital Technology Corporation Efficient frame tracking in mobile receivers
WO2005086370A1 (en) * 2004-02-25 2005-09-15 Thomson Licensing S.A. Method and apparatus for code tracking in code division multipe access (cdma) systems
US8107512B2 (en) * 2004-03-08 2012-01-31 Thomson Licensing Method and apparatus for robust automatic frequency control in CDMA systems with constant pilot signals
KR100823129B1 (en) * 2004-08-18 2008-04-21 삼성전자주식회사 Apparatus and method for tracking for closely spaced multipath fading channel
US7369632B2 (en) * 2005-01-28 2008-05-06 Nokia Corporation Diversity-mode delay lock loop circuit and associated method for a radio receiver
US20060262758A1 (en) * 2005-05-17 2006-11-23 Sumeet Sandhu Distributed communications for wireless networks
CN101297539A (en) * 2005-10-25 2008-10-29 日本电气株式会社 Mobile telephone unit, codec circuit used in that mobile telephone unit, and automatic telephone-speaker-sound-level adjustment method
US8275082B2 (en) * 2006-12-01 2012-09-25 Broadcom Corporation Method and system for delay locked loop for rake receiver
US7738548B2 (en) 2007-01-08 2010-06-15 Harris Corporation System and method for communicating at low signal-to-noise ratio using injected training symbols
US8312551B2 (en) * 2007-02-15 2012-11-13 Harris Corporation Low level sequence as an anti-tamper Mechanism
US7937427B2 (en) * 2007-04-19 2011-05-03 Harris Corporation Digital generation of a chaotic numerical sequence
US8611530B2 (en) * 2007-05-22 2013-12-17 Harris Corporation Encryption via induced unweighted errors
US7921145B2 (en) * 2007-05-22 2011-04-05 Harris Corporation Extending a repetition period of a random sequence
US7995757B2 (en) * 2007-05-31 2011-08-09 Harris Corporation Closed galois field combination
US7970809B2 (en) * 2007-06-07 2011-06-28 Harris Corporation Mixed radix conversion with a priori defined statistical artifacts
US7962540B2 (en) * 2007-06-07 2011-06-14 Harris Corporation Mixed radix number generator with chosen statistical artifacts
US7974413B2 (en) * 2007-06-07 2011-07-05 Harris Corporation Spread spectrum communications system and method utilizing chaotic sequence
US7835099B2 (en) 2007-06-29 2010-11-16 Seagate Technology Llc Method and system for error checking in a bit-patterned media
US8005221B2 (en) * 2007-08-01 2011-08-23 Harris Corporation Chaotic spread spectrum communications system receiver
US7995749B2 (en) * 2007-10-30 2011-08-09 Harris Corporation Cryptographic system configured for extending a repetition period of a random sequence
US8180055B2 (en) * 2008-02-05 2012-05-15 Harris Corporation Cryptographic system incorporating a digitally generated chaotic numerical sequence
US8363830B2 (en) * 2008-02-07 2013-01-29 Harris Corporation Cryptographic system configured to perform a mixed radix conversion with a priori defined statistical artifacts
US8040937B2 (en) * 2008-03-26 2011-10-18 Harris Corporation Selective noise cancellation of a spread spectrum signal
US8139764B2 (en) * 2008-05-06 2012-03-20 Harris Corporation Closed galois field cryptographic system
US8320557B2 (en) 2008-05-08 2012-11-27 Harris Corporation Cryptographic system including a mixed radix number generator with chosen statistical artifacts
US8145692B2 (en) * 2008-05-29 2012-03-27 Harris Corporation Digital generation of an accelerated or decelerated chaotic numerical sequence
US8064552B2 (en) * 2008-06-02 2011-11-22 Harris Corporation Adaptive correlation
US8068571B2 (en) * 2008-06-12 2011-11-29 Harris Corporation Featureless coherent chaotic amplitude modulation
US8325702B2 (en) * 2008-08-29 2012-12-04 Harris Corporation Multi-tier ad-hoc network in which at least two types of non-interfering waveforms are communicated during a timeslot
US8165065B2 (en) 2008-10-09 2012-04-24 Harris Corporation Ad-hoc network acquisition using chaotic sequence spread waveform
US8406276B2 (en) * 2008-12-29 2013-03-26 Harris Corporation Communications system employing orthogonal chaotic spreading codes
US8351484B2 (en) * 2008-12-29 2013-01-08 Harris Corporation Communications system employing chaotic spreading codes with static offsets
US8457077B2 (en) * 2009-03-03 2013-06-04 Harris Corporation Communications system employing orthogonal chaotic spreading codes
US8428102B2 (en) * 2009-06-08 2013-04-23 Harris Corporation Continuous time chaos dithering
US8509284B2 (en) * 2009-06-08 2013-08-13 Harris Corporation Symbol duration dithering for secured chaotic communications
US8428103B2 (en) * 2009-06-10 2013-04-23 Harris Corporation Discrete time chaos dithering
US8363700B2 (en) * 2009-07-01 2013-01-29 Harris Corporation Rake receiver for spread spectrum chaotic communications systems
US8369376B2 (en) * 2009-07-01 2013-02-05 Harris Corporation Bit error rate reduction in chaotic communications
US8340295B2 (en) * 2009-07-01 2012-12-25 Harris Corporation High-speed cryptographic system using chaotic sequences
US8406352B2 (en) * 2009-07-01 2013-03-26 Harris Corporation Symbol estimation for chaotic spread spectrum signal
US8385385B2 (en) * 2009-07-01 2013-02-26 Harris Corporation Permission-based secure multiple access communication systems
US8428104B2 (en) * 2009-07-01 2013-04-23 Harris Corporation Permission-based multiple access communications systems
US8379689B2 (en) * 2009-07-01 2013-02-19 Harris Corporation Anti-jam communications having selectively variable peak-to-average power ratio including a chaotic constant amplitude zero autocorrelation waveform
US8848909B2 (en) * 2009-07-22 2014-09-30 Harris Corporation Permission-based TDMA chaotic communication systems
US8369377B2 (en) * 2009-07-22 2013-02-05 Harris Corporation Adaptive link communications using adaptive chaotic spread waveform
US8345725B2 (en) 2010-03-11 2013-01-01 Harris Corporation Hidden Markov Model detection for spread spectrum waveforms
US8995597B2 (en) * 2010-04-16 2015-03-31 Taiwan Semiconductor Manufacturing Company, Ltd. Digital second-order CDR circuits

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5737362A (en) 1995-12-18 1998-04-07 Electronics And Telecommunications Research Institute Delay-locked loop code tracking system for receiver of a code spread communication system
US5768323A (en) * 1994-10-13 1998-06-16 Westinghouse Electric Corporation Symbol synchronizer using modified early/punctual/late gate technique
US5832023A (en) * 1994-08-16 1998-11-03 Nokia Mobile Phones Ltd. Spread spectrum receiver using absolute-value determination for code tracking
US6201828B1 (en) * 1998-11-12 2001-03-13 Nortel Networks Limited Fine estimation of multipath delays in spread-spectrum signals
US6205167B1 (en) * 1997-12-23 2001-03-20 Philips Electronics North America Corporation Apparatus and method for code tracking in an IS-95 spread spectrum communications system

Family Cites Families (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2720076B2 (en) * 1989-07-17 1998-02-25 京セラ株式会社 Automatic calibration apparatus for direct sequence spread spectrum receiver
US5390207A (en) * 1990-11-28 1995-02-14 Novatel Communications Ltd. Pseudorandom noise ranging receiver which compensates for multipath distortion by dynamically adjusting the time delay spacing between early and late correlators
US5134407A (en) * 1991-04-10 1992-07-28 Ashtech Telesis, Inc. Global positioning system receiver digital processing technique
US5590160A (en) * 1992-12-30 1996-12-31 Nokia Mobile Phones Ltd. Symbol and frame synchronization in both a TDMA system and a CDMA
FI943249A (en) * 1994-07-07 1996-01-08 Nokia Mobile Phones Ltd A method for controlling the receiver and the receiver
US5659573A (en) * 1994-10-04 1997-08-19 Motorola, Inc. Method and apparatus for coherent reception in a spread-spectrum receiver
US5579345A (en) * 1994-10-13 1996-11-26 Westinghouse Electric Corporation Carrier tracking loop for QPSK demodulator
DE69635315D1 (en) * 1995-06-30 2005-11-24 Interdigital Tech Corp Kodeverteilvielfachzugriffskommunikationssystem
US6633255B2 (en) * 1995-10-09 2003-10-14 Qualcomm Inc. Method for open loop tracking GPS signals
US6549559B2 (en) * 1997-12-23 2003-04-15 Koninklijke Philips Electronics N.V. Apparatus and method for locking onto a psuedo-noise code in an IS-95 spread spectrum communications system
US6370397B1 (en) * 1998-05-01 2002-04-09 Telefonaktiebolaget Lm Ericsson (Publ) Search window delay tracking in code division multiple access communication systems
DE19839018C2 (en) * 1998-08-27 2002-04-04 Infineon Technologies Ag Tracking method and assembly for implementing the method
US6614834B1 (en) * 1998-09-08 2003-09-02 The Board Of Trustees Of The Leland Stanford Junior University Communication arrangement and method with fast tracking receiver for spread spectrum signals
GB9909827D0 (en) * 1999-04-29 1999-06-23 Roke Manor Research Improvements in or relating to delay lock loops
JP3694201B2 (en) 1999-11-09 2005-09-14 三菱電機株式会社 Spread spectrum communication demodulation device
US6483867B1 (en) * 1999-11-22 2002-11-19 Nokia Mobile Phones Ltd. Tracking loop realization with adaptive filters
KR100373338B1 (en) 2000-06-24 2003-02-25 주식회사 팬택앤큐리텔 Apparatus for tracking CDMA code timing
JP2002290279A (en) 2001-03-28 2002-10-04 Toshiba Corp Synchronism tracking device and wireless communication terminal
US6456648B1 (en) * 2001-10-01 2002-09-24 Interdigital Technology Corporation Code tracking loop with automatic power normalization

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5832023A (en) * 1994-08-16 1998-11-03 Nokia Mobile Phones Ltd. Spread spectrum receiver using absolute-value determination for code tracking
US5768323A (en) * 1994-10-13 1998-06-16 Westinghouse Electric Corporation Symbol synchronizer using modified early/punctual/late gate technique
US5737362A (en) 1995-12-18 1998-04-07 Electronics And Telecommunications Research Institute Delay-locked loop code tracking system for receiver of a code spread communication system
US6205167B1 (en) * 1997-12-23 2001-03-20 Philips Electronics North America Corporation Apparatus and method for code tracking in an IS-95 spread spectrum communications system
US6201828B1 (en) * 1998-11-12 2001-03-13 Nortel Networks Limited Fine estimation of multipath delays in spread-spectrum signals

Non-Patent Citations (7)

* Cited by examiner, † Cited by third party
Title
3GPP TSG RAN, UE Radio Transmission and Reception (FDD), 3G TS 25.101, V3.2.0, Mar. 2000.
Floyd M. Gardner, Interpolation in Digital Modems-Part I: Fundamentals, IEEE, Transactions on Communications, vol. 41, No. 3, pp. 501-507, Mar. 1993.
Gardner et al., Interpolation in Digital Modems-Part II: Implementation and Performance, IEEE Transactions on Communications, vol. 41, No. 6, pp. 998-1008, Jun. 1993.
Jack K. Holmes, Coherent Spread Spectrum Systems, John Wiley and Sons Inc., pp. 475-481 and pp. 80-81, New York, 1982.
Latva-aho et al., Quasi-Coherent Delay-Locked Loops for Fading Channels.
Lim et al., Analysis of Decimator-Based Full-Digital Delay-Locked PN Code Tracking Loops for Bandlimited Direct-Sequence Spread-Spectrum Signals in AWGN, IEICE Transactions on Communications, vol. E00-A, No. 1, Jan. 1998.
Su et al., Performance of Combined DDLL and AGC Loop Direct-Sequence Spread-Spectrum Systems, IEEE Transactions on Communications, vol. 48, No. 9, pp. 1455-1458, Sep. 2000.

Cited By (40)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040184533A1 (en) * 1997-03-14 2004-09-23 Microsoft Corporation Motion video signal encoder and encoding method
US7139313B2 (en) 1997-03-14 2006-11-21 Microsoft Corporation Digital video signal encoder and encoding method
US7072396B2 (en) * 1997-03-14 2006-07-04 Microsoft Corporation Motion video signal encoder and encoding method
US7154951B2 (en) * 1997-03-14 2006-12-26 Microsoft Corporation Motion video signal encoder and encoding method
US20040184535A1 (en) * 1997-03-14 2004-09-23 Microsoft Corporation Motion video signal encoder and encoding method
US20050220188A1 (en) * 1997-03-14 2005-10-06 Microsoft Corporation Digital video signal encoder and encoding method
US6658242B1 (en) * 1997-12-12 2003-12-02 Thomson Licensing S.A. TDMA wireless telephone system with independently tracked demodulation parameters
US20060098719A1 (en) * 2000-01-14 2006-05-11 Jens Baltersee Adaptive code-tracking receiver for direct-sequence code-division multiple access (CDMA) communications over multipath fading channels and method for signal processing in a rake receiver
US7333532B2 (en) 2000-01-14 2008-02-19 Agere Systems Inc. Adaptive code-tracking receiver for direct-sequence code-division multiple access (CDMA) communications over multipath fading channels and method for signal processing in a rake receiver
US7203220B2 (en) 2000-01-14 2007-04-10 Agere Systems Inc. Method and rake receiver for code-tracking in communication systems
US7142585B2 (en) * 2000-01-14 2006-11-28 Agere Systems Inc. Adaptive code-tracking receiver for direct-sequence code-division multiple access (CDMA) communications over multipath fading channels and method for signal processing in a rake receiver
US7167506B2 (en) 2000-03-03 2007-01-23 Agere Systems Inc. Method and rake receiver for phasor estimation in communication systems
US20010038665A1 (en) * 2000-03-03 2001-11-08 Jens Baltersee Method and rake receiver for phasor estimation in communication systems
US20020169067A1 (en) * 2001-01-04 2002-11-14 Janssen Marcel J.G. Rejuvenating SAPO molecular sieve by freeze drying
US20020134908A1 (en) * 2001-01-24 2002-09-26 Applied Optoelectronics, Inc. Method for determining photodiode performance parameters
US6633603B2 (en) * 2001-10-01 2003-10-14 Interdigital Technology Corporation Code tracking loop with automatic power normalization
US20090213911A1 (en) * 2001-10-01 2009-08-27 Interdigital Technology Corporation Code tracking loop with automatic power normalization
US6775341B2 (en) * 2001-11-30 2004-08-10 Motorola, Inc. Time recovery circuit and method for synchronizing timing of a signal in a receiver to timing of the signal in a transmitter
US20030108136A1 (en) * 2001-11-30 2003-06-12 Fan Wang Time recovery circuit and method for synchronizing timing of a signal in a receiver to timing of the signal in a transmitter
US7006557B2 (en) * 2002-01-31 2006-02-28 Qualcomm Incorporated Time tracking loop for diversity pilots
US20100215084A1 (en) * 2002-04-29 2010-08-26 Interdigital Technology Corporation Simple and robust digital code tracking loop for wireless communication systems
US9525455B2 (en) 2002-04-29 2016-12-20 Interdigital Technology Corporation Simple and robust digital code tracking loop for wireless communication systems
US8379694B2 (en) * 2002-04-29 2013-02-19 Interdigital Technology Corporation Simple and robust digital code tracking loop for wireless communication systems
US20030202495A1 (en) * 2002-04-30 2003-10-30 Frank Poegel Power normalization in WLAN receivers
US7245588B2 (en) 2002-04-30 2007-07-17 Advanced Micro Devices, Inc. Power normalization in WLAN receivers
US20030231703A1 (en) * 2002-06-17 2003-12-18 Agilent Technologies, Inc. Rake receiver delay line design
US7190709B2 (en) 2002-11-04 2007-03-13 Advanced Micro Devices, Inc. Early-late correlation for timing error correction in data communication receivers
DE10251322A1 (en) * 2002-11-04 2004-05-19 Advanced Micro Devices, Inc., Sunnyvale Early-late correlation to the timing error correction in data communication receivers
DE10251322B4 (en) * 2002-11-04 2006-10-26 Advanced Micro Devices, Inc., Sunnyvale Early-late correlation to the timing error correction in data communication receivers
US20040088609A1 (en) * 2002-11-04 2004-05-06 Advanced Micro Devices, Inc. Early-late correlation for timing error correction in data communication receivers
US20040170911A1 (en) * 2003-02-26 2004-09-02 Tomoyuki Shimada Electrophotographic photoreceptor, and image forming method, image forming apparatus and process cartridge for image forming apparatus using the electrophotographic photoreceptor
US7724817B2 (en) * 2004-11-08 2010-05-25 Interdigital Technology Corporation Method and apparatus for estimating the step-size of an adaptive equalizer
US20090129458A1 (en) * 2004-11-08 2009-05-21 Interdigital Technology Corporation Method and apparatus for estimating the step-size of an adaptive equalizer
US7742518B2 (en) * 2005-11-28 2010-06-22 Honeywell International Inc. Discriminator function for GPS code alignment
US20070121708A1 (en) * 2005-11-28 2007-05-31 Honeywell International, Inc. Discriminator function for GPS code alignment
EP2161845A1 (en) * 2007-06-06 2010-03-10 Masshall Limited A multipath tracking device and method in a cdma communication system
EP2161845A4 (en) * 2007-06-06 2011-07-27 Masshall Ltd A multipath tracking device and method in a cdma communication system
US9923596B2 (en) * 2014-05-15 2018-03-20 Mitsubishi Electric Corporation Demodulation apparatus
US20170155422A1 (en) * 2014-11-27 2017-06-01 Lg Electronics Inc. Rake receiver and receiving method thereof
US9793946B2 (en) * 2014-11-27 2017-10-17 Lg Electronics Inc. Rake receiver and receiving method thereof

Also Published As

Publication number Publication date Type
EP1433266A1 (en) 2004-06-30 application
EP1433266A4 (en) 2005-02-02 application
US7010020B2 (en) 2006-03-07 grant
DE60207747T2 (en) 2006-07-27 grant
DE60231260D1 (en) 2009-04-02 grant
US20040057506A1 (en) 2004-03-25 application
DE60207747D1 (en) 2006-01-05 grant
US20090213911A1 (en) 2009-08-27 application
US6633603B2 (en) 2003-10-14 grant
CN1561582B (en) 2010-12-08 grant
CN1561582A (en) 2005-01-05 application
EP2056485A1 (en) 2009-05-06 application
JP2007189720A (en) 2007-07-26 application
DK1433266T3 (en) 2006-04-03 grant
CA2462504A1 (en) 2003-04-10 application
WO2003030389A1 (en) 2003-04-10 application
JP2005505190A (en) 2005-02-17 application
JP4035108B2 (en) 2008-01-16 grant
US7529292B2 (en) 2009-05-05 grant
US20030063657A1 (en) 2003-04-03 application
ES2250650T3 (en) 2006-04-16 grant
EP1433266B1 (en) 2005-11-30 grant
US20060126574A1 (en) 2006-06-15 application
JP4227178B2 (en) 2009-02-18 grant

Similar Documents

Publication Publication Date Title
US6459883B2 (en) Generic finger architecture for spread spectrum applications
US5638362A (en) Correlation detector and communication apparatus
US5724384A (en) PN code sync device using an adaptive threshold
US5790537A (en) Interference suppression in DS-CDMA systems
US6330271B1 (en) CDMA receiver that shares a tracking device among multiple rake branches
EP1089452A1 (en) Fractional sample timing error estimation for W-CDMA
US20040264554A1 (en) User terminal parallel searcher
US6208683B1 (en) Receiving apparatus for use in CDMA type mobile radio communication system comprising a plurality of path receivers each including a follow-up path detection unit
US7167456B2 (en) Apparatus for estimating propagation path characteristics
US6816541B1 (en) Spread spectrum interference cancellation
US6650692B2 (en) CDMA receiver
US6661835B1 (en) Receiving device and channel estimator for use in a CDMA communication system
US20040161022A1 (en) Efficient back-end channel matched filter (CMF)
US20020045433A1 (en) Method and arrangement for reducing frequency offset in a radio receiver
EP0932263A2 (en) Method for finger assignment in CDMA rake-receiver
US6901106B1 (en) Delay lock code tracking loop employing multiple timing references
US7010073B2 (en) Delay lock loops for wireless communication systems
US7443826B1 (en) Method and apparatus for automatic frequency control in a CDMA receiver
EP0820156A2 (en) Reception timing detection circuit of CDMA receiver and detection method
US6507605B1 (en) Rake receiver in direct spreading CDMA transmission
US20080125070A1 (en) Method and apparatus for automatic frequency correction with a frequency error signal generated by block correlation of baseband samples with a known code sequence
EP0716520A1 (en) Cdma demodulation circuit and demodulating method
US20020131534A1 (en) System and method for multistage interference cancellation
US6370397B1 (en) Search window delay tracking in code division multiple access communication systems
US20010038665A1 (en) Method and rake receiver for phasor estimation in communication systems

Legal Events

Date Code Title Description
AS Assignment

Owner name: INTERDIGITAL TECHNOLOGY CORPORATION, DELAWARE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BULTAN, AYKUT;GRIECO, DONALD;REEL/FRAME:012450/0842

Effective date: 20011221

FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

FPAY Fee payment

Year of fee payment: 12